Packets of Interest 11-11-16

I read two interesting articles on VTP (Cisco’s VLAN Trunking Protocol) this week.

The first is an older article from networkworld.com that reminds us all that VTP clients are also capable of updating VLANs on the network, not just servers.

When I first heard that a VTP client can update a VTP server under the right conditions, I was frankly a non-believer. No way. I’d seen evidence to the contrary in several documents at cisco.com and in Cisco courses – but all the evidence was written, without my doing any experiments. So, I spent some time experimenting a few years ago, and found that it’s true – clients can overwrite VTP server’s VLAN databases.

The second article comes from etherealmind.com and is one of the only positive articles I’ve ever read about VTP. Greg’s take is that VTP is not inherently bad but instead the way network engineers deploy it is the reason it’s capable of causing so much damage.

A lot of people regard Cisco’s Virtual Trunking Protocol(VTP) as nothing but trouble. Frankly it’s hard to find many people who will implement it on their network and most people have war stories about full site outages caused by VTP and switch installs. I find this baffling – it’s a great technology that dramatically reduces time, configuration errors, and improves troubleshooting – features that we should all embrace and use wherever we can. In this post, I want to suggest a different design method for effectively using VTP in your network.